Valve mechanism for rock drills



June 2, 1931. w. A. SMITH, JR

VALVE MECHANISM FOR ROCK DRILLS Filed Nov. 22, 1928 INV ENTOR. PEI/wa :71" BY/ H18 ATTORNEY Patented June 2, 1931 .UNITED STATES PATENT- "oFFIca rseaisz W'ILLIAM' A. SMITH, JR OF PHILLIPSBUBG, NEW JERSEY, ASSIGIIGBQTO IN'GERSOLL- RAND COMPANY, JERSEY CITY, NEVJ JERSEY, A CORPORATION OF NEVI JERSEY vAtvEMnc iANisi/r roa Boer: rarer-s 1 Application filed November 22,1928. Serial No. 321,133. a

, This invention relates to rock drills, but more'particularly to avalve mechanism for rock drills of the fluid actuated type.

One object of the invention is to maintain one end of a valve of the oscillatory plate type firmly seated during the admissionof pressure fluid into the cylinder. sult maybe brought about by dividing the valve chamber into a plurality of pressure chambers, each one of which is in direct communication with a pressure fluid supply through separate and distinct channels, and

the arrangement is such that when pressure fluid is. being drawn from one pressure chamber into the cylinder, a-pressure equal to line-pressure will exist in the other pressure'chamber to act on the valve for maintaining said valve firmly seated over the inlet passage.

Other objects will be in part obvious and in part pointed out hereinaiter. I

In the drawings illustrating the invention and in which similari'eference characters refer to similar parts,

Figure 1 is a sectional elevation of a rock drill aswill the invention,

Figure 2 is a transverse view taken through Figure 1 on theline 2+2 looking in the direction indicated by the arrows, and

of so much serve to lllustrate Figure 3 is a similar'view taken through Figure 1 on the line 8-8 looking in the direction indicated by the arrows.

Referring to the drawings, the invention is shown embodied in a rock drill designated by A and comprising a cylinder B in which is' disposed a reciprocatory hammer piston C to deliver blows to a working implement (not shown). The cylinder B has a free exhaust port D which is controlled by the piston C.

"In the rearward end ofthe cylinder B is an enlarged bore E into which extends a boss F of a back head G seated on the-rearward end of the cylinder-A. The back head This re- G may be'of a 'well known type and maybe secured to the cylinderA in any well known manner as for instance'by" side bolts H disposed on opposite sidesso'f the drill for clampingthe casing parts of the drill securely together. 7 Q

The back head G is provided with a throttle valve chamber J in which is disposed a throttle valve K of the rotary type having a lever L whereby said throttle valvevmay be manipulated. The throttle" valve Khas a central chamber O into which-pressure fluid from a sultable source may be introduced, and in theside oi the throttle valve is a port P which, in the openpositionofthe throttle'valve, registers with a passage Q,

leading to a supply reservoir R end of the back head. I The drill A. is equipped with suitable in the front mechanism for'inducin'g'a step by step ror tary movement of the piston and conse quently of the working; implement through the medium of suitable i chuck mechanism (not shown). The means provided for this purpose comprises a "rifle bar ,5 which is slidably interlocked with the pistonC and has ajheadTwhich carries spring'pressed pawls adapted toengage teethV of'a rotation ratchet'VV disposedjin the bore E and serving as aseajt for the back'head Gr.

Disposed in the innermost end ofthe bore E is a "suitable valve mechanism designated by X for controlling the admission of pressure fluid into the cylinder to actuate the piston C. The valve mechanism X constructed accordance with thev present invention comprises a pair of plates Y, and'Z. The plate Z forms a' closure for the rearward end of the cylinder B and has-a flat rear-f ward surface which acts as a valve seat '6 tion tothe'functions described, the plate Z also acts as a closure for one side' of a valve chamber 0 preferably formed entirely in theplate Y for the reception of a distributing valve d. r

The distributing valve (Z is of the oscillatory plate type and is preferably in the 5 form of a disk having tapered surfacese and f at opposite ends converging from opposite sides of the valve to form wings c and f; The point of convergence of the tapered surfaces 6 and f is on the transverse median line of the valve (Z thus forming apices g and h whereon the valve d is adapted to. rock from one limiting position to another. It is in the plane wherein the apices g and h liethat the valve attains its maximum thickness. The distance through the valve, at this point, however, is'preferably small so that as the valve rocks from one limiting position to the other, the apices g and it will travel through onlya small arc.

The valve chamber 0 is provided with an intermediate restricted portion 7' formed in this .instance by an integral ribj on the plate Y. The restricted portion jisof a depth substantially equal to the thickness of the valve at the point of the apices so that said apices g and h willbe in body contact with the boundingsurface'of the restricted portion. j, as for instance, with the surface 6 of the plate Z and witha surface 70 of the rib 77'whicl1 overlies the plate Z. Therib j also serves as a stop for the valve and opposite wings e and f of the valve are adapted to seat alternately onthe surfaces b and is. I

with an enlarged central portionw-and reduced neck portion o definingthe curved inneredges of a pairof arcuate slots separated at their terminal ends by the neck portions of the rib 'j, to-form separatepressure chambers 0 and p into which pressure fluid-from the supply reservoir B may be introduced Kthrough supply passages '9 formed in this instance in the rotation ratchet \V. The pressurecha mbers 0 and ;0 may be in the formof arcuate recesses of sufficient area to accommodate-a substantial volnmeof .pressure fluid and may be" so located that they overliea substantial area or areas of the outer portion of the valve (Z and preferably also over the inlet openings .of the inlet passages a-nd'ls leading to the rearward and forward ends respectively of the cylinder B. .As is customary in valves of-the type illustrated, the body portion of the valve (Z is of somewhat'smaller diameter than the valve chamber wherein it is disposed to permit a free flow of pressure fluid over a'subst'antial ($0 portion of the raised end of'the valve. In 7 certainlcases where uniformity of pressure throughout the valve chamberisnot considered objectionable,- the valve may bein the form of a true disk and clearance will 165 therefore exist betweeiijallfpoints of the The rib portion j is preferably formed pressure fluid from one pressure chamber to another at this point; p

The operation of the device is as follows: Pressure fluid flowing from the throttle valveK into thesupply reservoir R will flow through the supply passages 9 into both ofthe pressure chambers 0 and. p. 'VVith the left hand end of'the valve raised, as illustrated, pressure fluid will then flow through the inlet passage 1' into the rearward end of the cylinder to impel the piston C forwardly.j During this movement of the piston,

the air in the front end of the cylinder will be compressed and will flow through the inlet passage 8 to act against the tapered surface 7 of the seated portion of the valve toassistthe suction of the pressure fluid flowing over the raised end of the valveto tip the valve to its other limiting position immediately after'the piston G overruns the free exhaust port D, in which case there is an abrupt; drop in pressure inthe rearward end of thecylinder. i, l a

During the time, however, that pressure fluidis. being admitted to the rearward end of the cylinder to drive the piston .C for? "wardly, the pressure 111 the pressure chamber pwill be of somewhat less value than line pressure, due to the expansion of .the

pressure fluid, not only. in the cylinder. but

also in the pressurechamberp. Inasmuch that the pressure chamber 79 is completely separated from the pressure chamber 0 the drop in pressure in the chamber piresulting during the admission of pressureifluid into the cylinder will not be communicated to the pressure fluid existing in the pressure chamber 0. Thereforethe'entiresurface-e ofthe seated end of the valve will be ex- .posedto full line pressure, or in otherzwords, to a pressure somewhat in excessof. that existingin the'pressnre chamber p. As a result ofthis feature, the valve will be held firmly inits limiting position and the tend ency'of the seated endof the valve, to be repeatedly raised from. itsseat byi'the suction'created by the pressure fluid flowing overj theraised end. of the valve will be eliminated. The piston G willthusbe free to deliver aheavybl'ow against the working implement without having some of its force absorbed by acushion'of live pressure fluid in: the front end of the cylinder as would be the case were the valve (Z allowed to tremble on its seat. About the time the piston C is ready to deliver its blow to the working implement, the compression in theinlet passage 8 and the air flowing over-the raised end of the valve (Z will tilt the valve to its other extreme position. In the new position of the valve, pressure fluid will flow over the right 7 isting in the pressure chamber 10 by the valve (Z, that is, by the apices g and h and the projections a which effectively prevent communication between the pressure chambers through the valve chamber.

By maintaining the valve firmly seated during the rearward stroke of the piston, it will be impossible for the pressure fluid to leak or flow into the rearward end of the cylinder to augment the compression created by the piston and thepiston C is therefore 1 capable of advancing rearwardly the .full

distance of its nominal strokeinstead of being reversed immediately after the exhaust port D is uncovered. This feature of course results in greater drilling efiiciency than would be the case ifthe piston were reversed before running the full course of its nominal stroke.

During the rearward stroke the piston will uncover the exhaust port D to open the front end of the cylinder and the space heneath the raised end of the valve to the atmosphere and the compression created by the piston on the rearward end of the cylinder and the suction of the air flowing over the raised end of the valve will then again actuate the valve to its initial position.

I claim:

1. In a fluid actuated rock drill, the combination of acylinder and a reciprocatory piston, a valve chest comprising a pair of plates one of which plates is recessed to form a cylindrical valve chamber, a valve seat on one of the plates, a rib on the other plate extending across the valve chamber to form an intermediate restricted portion in the valve chamber, said rib having an enlarged center portion and reduced neck portions thereon defining the curved inner edges of a pair of arcuateslots separated at their terminal ends by the neck portions of the rib to form separate pressurechambers, 1n let passages leading from the pressure chainbers to the cylinders, an oscillatory disc (IllS-g her to-the other the peripheral bounding surfacefof the valve chamber to permit'the passage ofpressure fluid to the inlet passages, said valve'having an apex at each endto bear on the valve seat; and. the .rib for preventing the flow of pressure fluid from one pressure chamthrough the restricted portion.

2; In a fluid actuated rock drill, the combination of v a cylinder-and a reciprocatory piston, a valve'chest comprising a pair of plates one of which plates is recessed. to form a cylindrical valve chamber, a 1 valve seat on one of the plates, a rib on the other plate extending across thelvalve chamber to form an intermediate restricted portion, said r1'b having an enlarged center portion and reduced neck portions thereon defining the.

curved inner edges of a pair of arcuate slots separated at their terminal ends by the neck portions of the rib to form separate pressure chambers, said rib presenting a relatively broad flat surface to act as a valve stop, lnlet passages leading from the pressure chambers'to the cylinder, an oscillatory disc distributing valve in the valve chamber controlling the inlet passages, and having the major/portion of its periphery.

spaced from the peripheral bounding surface of the valve chamber to permit the passa e of pressure fluid to the inlet passages, an apex at each end of the valve to bear on the valve seat and the 1%, said valve being uniformly tapered from the apices to-the periphery at each side of the valve to form wings adapted to seat alternately on the valve seat and the rib for preventing the flow of pressure fluid from onepressure chamber to the other through the restricted portion.

3. In a fluid. actuated rock drill, the combination of-a cylinder and a .reciprocatory piston, a valve chest comprising a pair of I plates one of said'plates beingrecessed to rib havingan enlargedcenter portion and reduced neck portions thereon definlng the curved inner edgesof a pair of arcuate slots separated at their terminal endsby the neck portions of the rib to form separate pressure chambers, said rib presenting a relatively broad flat surface to act as a valve stop, inlet passages leading from the pressure chambers to the cylinder, an oscillatory disc distributing valve 1n the valve chamber controlling the inlet passages and; having the major portion of its "periphery spaced from the peripheral bounding surface of the valve chamber to permit thepassage of seat and the rib, wings on opp ositesides of the vapices being uniformly tapered from r the apices t0 the periphery anclaaclaptedto seat alternately .on the valve seat and the rib, and projections on opposite. sides of the valve lying in the plane ofthe apices" and having partly cylindrical surfaces to cooperate With the peripheral bounding sur- I faces of the valve'chamber for preventing theflow of pressure fluid fromone pres: .t sure chamber to another through the Valve chamber.. I I V In testimony whereof I- have signed this 7 p specification.

WILLIAM A; SMITH, Jm 

